1. Field of the Invention
The present invention relates generally to a method and an apparatus for protecting a wireless power receiver from excessive temperature caused by charging.
2. Description of the Related Art
Mobile terminals, such as cell phones, Personal Digital Assistants (PDAs), and the like are powered by rechargeable batteries, and they need separate charging devices to recharge the batteries. Typically, the charging device and the battery are electrically connected by contacting their contact terminals together.
However, such contact terminals are easily contaminated by dirt because they are exposed to the air, and thus battery charging may not be performed correctly. Also, when the contact terminals are exposed to moisture, charging may likely go wrong.
To solve this problem, wireless charging or contactless charging technologies have recently been developed and applied to various electronic devices.
The wireless charging technology uses wireless power transmission and reception, which enables, for example, a battery of a cell phone to be automatically charged just by placing the cell phone on a charging pad without a need of a separate charging connector. This technology is known in a form of wireless electric toothbrushes or wireless electric shaver. The wireless charging technology enhances waterproof performance and portability of the electronic device by charging them wirelessly without a need of a cable charger, and in the field of electric vehicles, relevant technologies are expected to be significantly developed.
In a wireless power receiver, rectifying alternate current power to direct current power and regulating the direct current power to a certain level may possibly create heat. The wireless power receiver monitors its temperature and stops receiving wireless power if the temperature rises above a predetermined threshold. Thus, the wireless power receiver may stop wireless charging due to a temperature rise and resume it when the temperature drops. Considering the importance of seamless wireless charging, the wireless power receiver may not perform such seamless wireless charging once it stops charging due to a high temperature until the temperature drops. To resume charging, it has to be connected to a wireless power transmitter again and the user has to wait until the connection is made, which may cause great inconvenience to the user.